The present invention deals with the development of a beryllium-7 radiotracer produced within the lattice of carbon black. Beryllium-7 has a 53-day half life and a 478 KeV gamma ray. The beryllium-7 solid carbon particles are produced by proton irradiation of pure carbon black. The activity concentration of beryllium-7 in carbon may be controlled by a variation in the duration of bombardment. Typically, there is produced 11 .mu.Ci/mg of carbon in two weeks bombardment at 50 .mu.A, but levels up to about 100 .mu.Ci/mg could be achieved at saturation. The activity concentration of the non-ionic surfactant suspension is typically 300-400 .mu.Ci/ml.
The gamma radiation of the beryllium-7 labeled carbon particles is sufficiently energetic that whole body counting allows the determination of the kinetics of clearance and the biodistribution of residual particulate material. A number of other useful applications can be made of this material. The product can be used in intestinal absorption of non-digestible particulate matter in animal models. The beryllium-7 labeled carbon has also been utilized to characterize the distribution of material intratracheally introduced in rodents. In a further application, the beryllium-7 labeled carbon can also be aerosolized and serve as a model for particulate matter associated with air pollution.